Single hit TP return (9.2%)
Full SA+AC+WS TP return (11.2%)
Not full SA+AC+WS TP return (10.2%)
Conclusion:
100% Triple Attack accuracy with SA+AC doesn't apply to WS.
Test info:
My hit rate was floored (Vicissitude, Mounted Champion, Voracious Violet, only HP cruor buff, no DEX+ or Acc/Skill+ gear) and it took me a while to get 11% TP on WS, just to show the max TP return was indeed 11% with all three hits connecting. The gear was the exact same in all scenarios with no Store TP. I was on THF/WAR to get access to Heavy Swing.
Edit: The 11% was attained without VV Atma, as you can see on the screenshot. My hit rate was so low that building TP took me ages, so I switched after that. The 10% TP screenshot couldn't have happened if the Regain tick kicked in, so obviously it was attained through a 2/3 hit connect on WS.